snow. >> a shoutout tonight. you warned us last night, we felt the whiplash today with temperatures. >> reporter: and it was whiplash. let me show you the dramatic change that folks went through. start with chicago and what happens here on this graphic is, you're going to look on the left side, yesterday's high temperature. so, places like chicago made it to 63. on the right side, that cold blue number, 30. that's the current temperature. so, big 30 to 40 degree drop. and tomorrow morning, just so all of you know, if you are putting out the holiday lights, look at how cold it's going to be. 22 chicago, 24 st. louis, 30, even, in memphis. so, this goes to the south, too. david? >> we always appreciate the heads up. ginger zee. thank you. it was last night here we showed you the dramatic pictures, how the weather, the fog created a holiday nightmare on a texas highway. these images taken moments after those hundred cars collided on that highway, two people were ki killed, more than 100 injured. tonight here, abc's ryan owens in texas with what authorities are now saying this was more than fog. it was a deadly combination of speed and a disappearing highway.